The SLS is the new heavy launch
system for NASA. The SLS configuration for EM-1 is considered Block 1,
the first configuration of the SLS evolution plan. The Shuttle-derived
design takes advantage of resources established for the Space Shuttle,
including the workforce, tooling, manufacturing processes, supply
chain, transportation logistics, launch infrastructure, and LOX/LH2
propellant infrastructure. An overview of the initial SLS Block 1
configuration that will first fly with the Orion in 2020 is shown in
Figure 1. The SLS enables many aspects of
the NASA core capabilities in addition to human exploration
initiatives. These include the reduction in mission duration, increased
mass margins, reductions in total spacecraft complexity, and
significant increases in payload volume. 1)2)3)4)

Created to provide sufficient launch
capability to enable human exploration missions beyond Earth orbit and
ultimately to Mars, NASA’s Space Launch System (SLS) rocket
represents a new asset, not only for human spaceflight, but also for a
variety of other payloads and missions with launch requirements beyond
what is currently available. The initial configuration of the vehicle,
on track for launch readiness in 2020, is designed to offer substantial
launch capability in an expeditious timeframe and to support evolution
into configurations offering greater launch capability via an
affordable and sustainable development path.

NASA is developing SLS in parallel
with two other exploration systems development efforts – the
Orion crew vehicle program and the Ground Systems Development and
Operations (GSDO) program. Orion is a four-person spacecraft designed
to carry astronauts on exploration missions into deep space. GSDO is
converting the facilities at NASA’s Kennedy Space Center (KSC) in
Florida into a next-generation spaceport capable of supporting launches
by multiple types of vehicles.

These capabilities are part of a
larger NASA strategy of working with commercial partners that will
support crew and cargo launches to the International Space Station,
while the agency focuses its development efforts on an incremental
approach to developing the systems necessary for human exploration
beyond Earth orbit and eventually to Mars. SLS is being designed with
performance margin and flexibility to support an evolvable human
exploration approach. (Figure 2).

Currently under construction, the
initial configuration of the vehicle will have the capability to
deliver a minimum of 70 t into low Earth orbit (LEO) and will be able
to launch a crew aboard the Orion spacecraft on into cislunar space on
its first flight, Exploration Mission-1 (EM-1) in 2020. The vehicle
will evolve to a full capability of greater than 130 t to LEO and will
be able to support a stepping-stone approach to human exploration
leading to the first footsteps on Mars.

The SLS initial Block 1
configuration stands 97 meters tall, including the Orion crew vehicle.
The vehicle’s architecture reflects NASA’s desire to meet
the mandates for heavy-lift capability in the U.S. congressional NASA
Authorization Act of 2010 in a manner that is safe, affordable, and
sustainable. After input was received from industry and numerous
concepts were reviewed, a shuttle-derived design was found to enable
the safest, most-capable transportation system in the shortest amount
of time for the anticipated near-term and long-range budgets.

The SLS operational scheme takes
advantage of resources established for the Space Shuttle Program,
including workforce, tooling, manufacturing processes, supply chains,
transportation logistics, launch infrastructure, and liquid oxygen and
hydrogen (LOX/LH2) propellants and allows the initial configuration of
the vehicle to be delivered with only one clean-sheet new development,
the Core Stage. In October 2015, the SLS Program completed its Critical
Design Review (CDR), the first time a NASA human-class launch vehicle
has reached that milestone since the Shuttle Program almost 40 years
ago.

The SLS Core Stage, which stores the
liquid oxygen (LOX) and liquid hydrogen (LH2) propellant for four Core
Stage engines, will stand 61 m tall and will have a diameter of 8.4 m,
sharing commonality with the space shuttle’s external tank in
order to enhance compatibility with equipment and facilities at Kennedy
Space Center and elsewhere. At Michoud Assembly Facility (MAF), outside
New Orleans, Louisiana, the last of six major welding manufacturing
tools for the Core Stage, the world’s largest space vehicle
welding tool, the 52m-tall Vertical Assembly Center (VAC), has been
installed and is being used by The Boeing Company, Core Stage prime
contractor, to weld barrel sections, rings and domes together to form
the propellant tanks for the stage.

Figure 1: SLS Block 1 70t Initial Configuration (image credit: NASA)

The Core Stage will be powered by
four RS-25 engines, which previously served as the Space Shuttle Main
Engine (SSME), taking advantage of 30 years of U.S. experience with
liquid oxygen and liquid hydrogen, as well as an existing U.S. national
infrastructure that includes specialized manufacturing and launching
facilities. These human-rated engines support the SLS goal of safety,
with a record of 100 percent mission success for the engines over 135
flights. At the end of the Space Shuttle Program, 16 RS-25 flight
engines and two development engines were transferred to the SLS Program
and placed in inventory at NASA’s Stennis Space Center, providing
enough engines for the first four flights of SLS.

While the SLS Program is heavily
focused on working toward first flight, efforts are already underway on
the evolution of SLS beyond the 70 t Block 1. As early as the second
launch of SLS, Exploration Mission-2, the vehicle will be augmented
with a low-thrust dual-use Exploration Upper Stage (EUS), providing
both ascent and in-space propulsion capabilities. This stage, which is
working toward a preliminary design review in late 2016, will upgrade
SLS to a performance of 105 t to LEO, and create a configuration that
will serve as a workhorse for “Proving Ground” missions in
cislunar space that will pave the way for further exploration. From
there, additional upgrades, including enhancements to the RS-25 engines
and upgraded boosters will ultimately evolve SLS to a configuration
capable of delivering more than 130 metric tons to LEO, the capability
identified as necessary for human missions to Mars.

Modifications to Stennis Test Stand
A-1 to support RS-25 testing were completed in 2014, and two test
series have already been completed in preparation for flight
certification of the SLS configuration of the engine, including a new
engine controller unit. The testing includes propellant pressure and
temperature inlet conditions that will both be higher with SLS than
with the shuttle, as well as other SLS-specific performance
requirements such as 109 percent thrust versus the shuttle’s
104.5 percent thrust. Stennis Test Stand B-2 is being refitted for the
SLS “green run” – the test firing of the first Core
Stage with four RS-25 engines beginning in 2017, which will be
NASA’s largest engine ground firing since stage tests of the
Saturn V in the 1960s.

The majority of the thrust for the
first two minutes of flight will come from a pair of Solid Rocket
Boosters, also of Space Shuttle Program heritage. The SLS is upgrading
the boosters from the four-segment version flown on the shuttle to a
more-powerful five-segment version. Each booster measures 54 m long and
3.7 m in diameter and is capable of generating up to 3.6 million pounds
of thrust, the most powerful flight boosters in the world. Although
largely similar to the SRBs used on the space shuttle, this upgraded
five-segment SRB includes improvements such as a larger nozzle throat
and an environmentally-benign insulation and liner material. In March
2015, the SLS configuration of the booster successfully underwent the
first of two Qualification Motor tests, and the second test is
scheduled for summer 2016.

In-space propulsion
for the 70 t Block 1 version of SLS will be provided by the Interim
Cryogenic Propulsion Stage (ICPS), a modified version of United Launch
Alliance’s Delta Cryogenic Second Stage (DCSS) flown on more than
20 launches of the Delta IV Evolved Expendable Launch Vehicle (EELV).
In order to support the currently planned initial test flight that
would send Orion on a circumlunar trajectory, the LH2 tank of the SLS
ICPS will be stretched 46 cm longer than the standard DCSS.

While the SLS Program is heavily
focused on working toward first flight, efforts are already underway on
the evolution of SLS beyond the 70 t Block 1. As early as the second
launch of SLS, Exploration Mission-2, the vehicle will be augmented
with a low-thrust dual-use Exploration Upper Stage (EUS), providing
both ascent and in-space propulsion capabilities. This stage, which is
working toward a preliminary design review in late 2016, will upgrade
SLS to a performance of 105 t to LEO, and create a configuration that
will serve as a workhorse for “Proving Ground” missions in
cislunar space that will pave the way for further exploration. From
there, additional upgrades, including enhancements to the RS-25 engines
and upgraded boosters will ultimately evolve SLS to a configuration
capable of delivering more than 130 metric tons to LEO, the capability
identified as necessary for human missions to Mars.

Figure 3: Welding is complete on
the largest piece of the core stage that will provide the fuel for the
first flight of NASA's new rocket, the Space Launch System, with the
Orion spacecraft in 2018. The core stage liquid hydrogen tank has
completed welding on the Vertical Assembly Center at NASA's Michoud
Assembly Facility in New Orleans. Standing more than 40 m tall and 8.4
m in diameter, the liquid hydrogen tank is the largest cryogenic fuel
tank for a rocket in the world. The liquid hydrogen tank and liquid
oxygen tank are part of the core stage — the "backbone" of the
SLS rocket that will stand at more than 61 m tall. Together, the tanks
will hold 733,000 gallons (2775 m3) of propellant and feed
the vehicle's four RS-25 engines to produce a total of 2 million pounds
of thrust (8896 kN) This is the second major piece of core stage flight
hardware to finish full welding on the Vertical Assembly Center. The
core stage flight engine section completed welding in April 2016. More
than 1.7 miles of welds have been completed for core stage hardware at
Michoud. Traveling to deep space requires a large rocket that can carry
huge payloads, and SLS will have the payload capacity needed to carry
crew and cargo for future exploration missions, including NASA's
Journey to Mars. 5)

The secondary
payload initiative for EM-1 takes advantage of several of these
capabilities and enables new opportunities for small spacecraft
developers. By utilizing planned unoccupied volume within the upper
stage adapter ring, the OSA (Orion Stage Adapter), increased mission
science and technology missions can be accommodated.

Figure 4: David Osborne, an Aerie
Aerospace LLC machinist at NASA's Marshall Space Flight Center in
Huntsville, Alabama, takes measurements prior to the start of precision
machining of the Orion stage adapter for NASA's new rocket, the SLS
(Space Launch System). The adapter will connect the Orion spacecraft to
the ICPS (Interim Cryogenic Propulsion Stage) for the first flight of
SLS with Orion in late 2018. The ICPS is the liquid oxygen/liquid
hydrogen-based system that will give Orion the big, in-space push
needed to fly beyond the moon before it returns to Earth. The adapter
also will carry 13 CubeSats that will perform science and technology
investigations that will help pave the way for future human exploration
in deep space, including the Journey to Mars (image credit: NASA, Sept.
29, 2016)

• July 26, 2019: NASA
Administrator Jim Bridenstine announced on July 25 the agency will
conduct a “Green Run” core stage test for the Space Launch
System rocket ahead of the upcoming Artemis 1 lunar mission. 6)

- The first eight minutes of every Artemis mission with NASA’s Space Launch System (SLS)
rocket will begin with core stage and solid rocket boosters producing
8.8 million pounds of thrust to launch the agency’s Orion
spacecraft to the Moon. NASA will test the rocket’s 212-foot tall
core stage- the tallest rocket stage the agency has ever built- with a
“Green Run” test on Earth before launch day to help ensure
mission success and pave the way for future Artemis missions carrying
crew to the Moon. Missions at the Moon will be a stepping stone to prepare for human exploration of Mars.

- During the Green Run testing, engineers will install the core stage that will send Orion to the Moon in the B-2 Test Stand at NASA’s Stennis Space Center
near Bay St. Louis, Mississippi for a series of tests that will build
like a crescendo over several months. The term “green”
refers to the new hardware that will work together to power the stage,
and “run” refers to operating all the components together
simultaneously for the first time. Many aspects will be carried out for
the first time, such as fueling and pressurizing the stage, and the
test series culminates with firing up all four RS-25 engines to
demonstrate that the engines, tanks, fuel lines, valves, pressurization
system, and software can all perform together just as they will on
launch day.

- “The SLS core stage is an
engineering feat that includes not only the largest rocket propellant
tanks ever built but also sophisticated avionics and main propulsion
systems,” said Lisa Bates, SLS deputy stages manager.
“While the rocket is designed to evolve over time for different
mission objectives, the core stage design will remain basically the
same. The Green Run acceptance test gives NASA the confidence needed to
know the new core stage will perform again and again as it is
intended.”

- The SLS core stage
includes state-of-the-art avionics, miles of cables and propulsion
systems and two huge liquid propellant tanks that collectively hold
733,000 gallons of liquid oxygen and liquid hydrogen to power the four
RS-25 engines. Together, they will produce more than 2 million pounds
of thrust to help send Artemis 1 beyond Earth’s orbit to the
Moon.

- The test program for the core
stage at Stennis will begin with installing the stage into the test
stand. Then, engineers will turn the components on one by one through a
series of initial tests and functional checks designed to identify any
issues. Those tests and checks will culminate in an eight-minute-long
test fire, mimicking the full duration of the stage’s first
flight with ignition, ascent and engine shutdown. The results of this
test also will provide important data that will confirm how the system
reacts as the fuel is depleted from the propellant tanks.

- “With Green Run, we verify
each individual component operates well within the core stage
system,” said Bates. “It’s more than testing.
It’s the first time the stage will come to life and be fully
operational from the avionics in the top of the core stage to the
engines at the bottom.”

- The test series is a collaborative
effort between a number of NASA field centers, programs and
contractors. The entire stage was built and manufactured
at NASA’s Michoud Assembly Facility in New Orleans. The
structural test articles, also built at Michoud, were shipped to
NASA’s Marshall Space Flight Center in Huntsville, Alabama, for
structural testing. The work done by Marshall’s test teams
certifies the structural integrity of the rocket’s core stage,
while Green Run shows that the integrated stage operates correctly. The
Stennis teams renovated the historic B-2 Test Stand used to test stages for multiple programs including the Saturn V and the space shuttle propulsion system in the 1970s.

- “Green Run is a historic
moment for NASA and Stennis for a number of reasons,” said Dr.
Richard Gilbrech, Director, Stennis Space Center. “For the first
time in NASA’s history, a launch vehicle will use flight hardware
for its first test, and the Stennis test stands will once again test
the core stage for Moon missions.”

- Historically, other NASA rockets
built to carry astronauts have used main propulsion test articles to
test the integrated engines and main propulsion system. The SLS program
is performing the stage testing with flight hardware. Once the
validation of the stage is complete, the entire stage will be checked
out, refurbished as needed, and then shipped to NASA’s Kennedy
Space Center in Florida for the Artemis 1 launch. The next time the
core stage engines roar to life will be on the launchpad at Kennedy.

- NASA is working to land the first
woman and next man on the Moon by 2024. SLS and Orion, along with the
Gateway in orbit around the Moon, are NASA’s backbone for deep
space exploration. SLS is the only rocket that can send Orion,
astronauts and supplies to the Moon on a single mission.

Figure 6: The “Green
Run” test of the core stage for NASA’s Space Launch System
(SLS) will be conducted at the B-2 Test Stand at NASA’s Stennis
Space Flight Center near Bay St. Louis, Mississippi. The historic test
stand has been used to test stages for multiple programs, including the
Saturn V and the space shuttle. The test stand was renovated to
accommodate the SLS rocket’s core stage, which is the largest
stage NASA has ever built (image credit: NASA)

• June 28, 2019: Aerojet
Rocketdyne recently delivered four RS-25 engines to NASA’s
Michoud Assembly Facility (MAF) for integration with the core stage of
NASA’s Space Launch System (SLS) in anticipation of the
rocket’s first flight on the Artemis 1 mission. 7)

- The RS-25 engine, an advanced
version of the Space Shuttle Main Engine, has a strong legacy of safely
and reliably powering human spaceflight. All four of the RS-25 engines
that will fly on the first SLS flight also flew during the Space
Shuttle Program; they have since been updated with new controllers and
adapted for the unique operating environment of SLS.

- The engines will be operated at a
higher power level than was used during the shuttle flights, providing
SLS with additional thrust (Figure 8).

- In addition to the RS-25 engines,
Aerojet Rocketdyne is also providing the RL10 engine that will power
the SLS upper stage, known as the Interim Cryogenic Propulsion Stage
(ICPS), as well as the composite overwrapped pressure vessels and
reaction control system thrusters. The ICPS is complete and ready for
integration with the rest of the SLS rocket components at Kennedy Space
Center.

Figure 8: An infographic about the first four engines and their flight history (image credit: Aerojet Rocketdyne)

- Earlier this year, Aerojet Rocketdyne delivered the
jettison motor, which is part of the Launch Abort System that will
ensure crew safety in the event of a launch or pad anomaly.
Additionally, Aerojet Rocketdyne has assisted in refurbishing the main
engine for the service module, and delivered the reaction control
system engines for the Orion crew module and eight auxiliary engines
for Orion’s European Service Module, which will ride atop the
SLS.

• June 27, 2019: The last of four structural test articles for NASA’s Space Launch System (SLS)
was loaded onto NASA’s Pegasus barge Wednesday, June 26, 2019, at
NASA’s Michoud Assembly Facility in New Orleans. The barge will
deliver the liquid oxygen (LOX) tank structural test article from
Michoud to NASA’s Marshall Space Flight Center in Huntsville,
Alabama, for critical structural testing. The liquid oxygen tank is one of two propellant tanks in the rocket’s core stage that will produce more than 2 million pounds of thrust (8896 kN) to help send Artemis 1,
the first flight of NASA’s Orion spacecraft and SLS, to the Moon.
The nearly 70-foot-long test article is structurally identical to the
flight version, which will hold 196,000 gallons of liquid oxygen super
cooled to minus 297 degrees Fahrenheit (-182ºC). 8)

- NASA is working to land the first woman and next man on the Moon by 2024. SLS is part of NASA’s backbone for deep space exploration, along with Orion and the Gateway in orbit around the Moon. SLS is the only rocket that can send Orion, astronauts and supplies to the Moon on a single mission.

• April 16, 2019: The boat-tail
structure, a fairing-like cover designed to protect the bottom end of
the core stage and the RS-25 engines, has been joined to one of the
most complicated and intricate parts of NASA’s Space Launch
System, the engine section. The engine section comprises the lowest
portion of the massive core stage of the deep space rocket. It houses four RS-25 engines that will produce 2 million pounds of thrust to send the rocket and NASA’s Orion spacecraft on lunar missions. 9)

- NASA is charged to get American astronauts to the Moon by 2024.
Our backbone for deep space exploration is SLS, the Orion spacecraft,
which will launch from NASA’s Kennedy Space Center in Florida on
missions to the Gateway in lunar orbit for missions to the surface of
the Moon. The agency will launch SLS and Orion on their first
integrated test flight around the Moon in 2020.

Figure 10: Technicians moved the
engine section and boat-tail for final assembly to a climate-controlled
area of NASA’s Michoud Assembly Facility in New Orleans.
Engineers will use the new tool and an internal access kit to finish
assembly. The tool, seen here in the blue frame around the bottom of
the engine section, allows more people to work on engine section tasks
at the same time — accelerating the pace of production and
reducing engine section integration and assembly time. This tool, along
with other production and processing improvements, will help enable the
core stage to be completed this year. The liquid oxygen tank structural
test article as well as the liquid hydrogen tank flight hardware for
the first mission of SLS are located just behind the engine section
(image credit: NASA)

- Technicians and engineers have qualified 3D printing to aid in the application of the thermal protection system to the smaller, more intricate parts of the rocket. Spray-on foam or traditional insulation
is applied to both large and small components of SLS; it protects the
rocket from heat during launch and keeps the propellant within the
large tanks cold.

- However, small
hardware or cramped areas like the internal ducts of the engine section
require technicians to either manually spray the foam on or apply a
foam casting using, in some cases, a 3D printed mold. During the
process, the foam, which is mixed and poured into the mold, expands to
perfectly fit the part. This decreases overall processing time by
reducing the need for complex and tedious post-process trimming.

- NASA and Boeing engineers
performed extensive development and qualification pour foam testing
early in the program. Using this data, the team developed a refined
process that reduced the amount of time required to certify individual
3D printed molds and allowed the team to spend more time focusing on
the critical requirements that must be met for each flight foam
application. This streamlined the process, from 3D printing to pour
application, and allowed for quicker processing times.

- NASA is charged to get American
astronauts to the Moon by 2024. Our backbone for deep space exploration
is SLS and Orion, which will launch from NASA’s Kennedy Space
Center in Florida to the Gateway in lunar orbit. From there, astronauts
will ultimately use a proposed human lunar landing system for missions
to the surface of the Moon.

Figure 11: A Space Launch System
(SLS) rocket model is prepped for wind tunnel testing by Courtney
Winski, aerospace engineer, at the Unitary Plan Wind Tunnel at NASA's
Langley Research Center in Hampton, Virginia. The pink
pressure-sensitive paint on the 0.8 percent scale model emits a bright
crimson glow when reacting with oxygen in the presence of high-pressure
airflows. This test allows engineers to understand changing pressures
exerted on the rocket during a launch (image credit: NASA)

• April 4, 2019: NASA is a step
closer to returning astronauts to the Moon in the next five years
following a successful engine test on Thursday at NASA’s SSC
(Stennis Space Center) near Bay St. Louis, Mississippi. The latest
“hot fire” was the culmination of four-plus years of testing for the RS-25 engines that will send the first four Space Launch System (SLS) rockets into space. 11)

- “This
completes four years of focused work by an exceptional Stennis test
team,” Stennis Director Rick Gilbrech said. “It represents
yet another chapter in Stennis’ long history of testing
leadership and excellence in support of this nation’s space
exploration efforts. Everyone involved should feel proud of their work
and contributions.”

- Thursday’s hot fire on Stennis’ A-1 Test Stand completed:

a) Acceptance testing of all 16
former space shuttle main engines that will help launch the first four
SLS missions. NASA has contracted with Aerojet Rocketdyne to build new
RS-25 engines for additional SLS missions, and work already is underway
to do so in the company’s factory in Canoga Park, California.

b) Developmental and flightworthy
testing for new controllers (plus one spare) to be used by the heritage
RS-25 engines for the first four missions.

c) A 51-month test series that
demonstrated RS-25 engines can perform at the higher power level needed
to launch the super heavy-lift SLS rocket.

- “Engines are now a
‘go’ for missions to send astronauts forward to the Moon to
learn and prepare for missions to Mars,” said Johnny Heflin,
deputy manager of the SLS Liquid Engines Office at NASA’s
Marshall Space Flight Center in Huntsville, Alabama. “We’re
ready to provide the power to explore the Moon and beyond.”

- The RS-25 rocket engine test era
began Jan. 9, 2015, with a 500-second – more than 8 minute
– hot fire of RS-25 developmental engine No. 0525 on the A-1 Test
Stand at Stennis. NASA tested the first SLS flight engine on March 10,
2016. Altogether, the agency has conducted 32 developmental and flight
engine tests for a total of 14,754 seconds – more than four hours
– of cumulative hot fire – all on the A-1 stand at Stennis.

- Having launched 135 space shuttle
missions, these main engines are considered the most tested engines in
the world. When the Space Shuttle Program ended in 2011, NASA still had
16 engines that ultimately were modified for SLS.

- These engines were originally
designed to perform at a certain power level, known as 100 percent.
Over time, the engines were upgraded to operate at higher and higher
power levels, up to 104.5 percent operating power level by the end of
the shuttle program. For SLS, that operating level has to be pushed
even higher.

- To help accomplish that, and to
interface with new rocket avionics systems, NASA designed and tested a
new engine controller, which serves as the “brain” of the
engine to help monitor engine operation and facilitate communication
between the engine and rocket. Early developmental testing at Stennis
provided critical information for designing the new controller.

Figure 13: NASA conducts a test
of RS-25 flight engine No. 2062 on April 4 on the A-1 Test Stand at
Stennis Space Center near Bay St. Louis, Miss. The test marked a major
milestone in NASA’s march forward to Moon missions. All 16 RS-25
engines that will help power the first four flights of NASA’s new
Space Launch System rocket now have been tested (image credit:
NASA/SSC)

- The first new flight engine
controller was tested at Stennis in March 2017, with a string of
controller hot fires to follow. The April 4 test marked the testing of
the 17th engine controller for use on SLS flights, providing enough for
all 16 heritage RS-25 engines.

- With development of the new
controllers, NASA had to test the new power level as well. First, it
was demonstrated that the engine could perform at the needed 111
percent power level. Next, NASA needed to prove a margin of operating
safety.

- In February 2018, operators pushed
the engine to 113 percent power for a total of 50 seconds. It
lengthened that firing time in two subsequent tests, until late this
February, when the engine was fired at 113 percent power for 430
seconds of a 510-second test.

- That set the
stage for Thursday’s successful test of flight engine No. 2062.
When this specific engine fires again, it will help send astronauts
aboard Orion around the Moon on a test flight known as Exploration Mission-2.

Figure 14: NASA is going to the
Moon and on to Mars, in a measured, sustainable way. Working with U.S.
companies and international partners, NASA will push the boundaries of
human exploration forward to the Moon. NASA is working to establish a
permanent human presence on the Moon within the next decade to uncover
new scientific discoveries and lay the foundation for private companies
to build a lunar economy (video credit: NASA, Published on 11 March
2019)

• March 19, 2019: NASA and its
industry partners continue their steady progress toward launching the
nation's newest rocket, NASA's Space Launch System (SLS). Engineers and
technicians at NASA's Marshall Space Flight Center in Huntsville,
Alabama, are integrating components with the SLS launch vehicle stage
adapter, which connects the core stage of the world's most powerful
rocket with its interim cryogenic propulsion stage (ICPS) that provides
the power to send Orion to the Moon. 12)

- One newly installed piece of
hardware — the frangible joint assembly — is designed to
break apart, allowing the hardware elements to separate during flight.
When a remote command is given, pistons fitted inside the ring assembly
push upward, instantaneously separating the upper part of the rocket
from the adapter and core stage.

- Frangible joint assemblies are
widely used in a variety of crewed and uncrewed spacecraft to
efficiently separate fairings or stages during launch and orbital
ascent and to execute payload deployment. Once the frangible joint
assembly is mated with the launch vehicle stage adapter and its
pneumatic actuation system is installed, Marshall SLS workers will ship
the hardware to NASA's Kennedy Space Center in Florida, where
technicians will "stack" the vehicle for final flight preparation.
NASA's Space Launch System and Orion spacecraft will pave the way for
human missions to the Moon and Mars and groundbreaking new discoveries.

• March 8, 2019: NASA will soon
return humans to the Moon for decades to come, and the system that will
transport astronauts from Earth to the Gateway near the Moon is
literally coming together. Building on progress in 2018,
most of the major manufacturing for the first mission is complete, and
this year, teams will focus on final assembly, integration, and
testing, as well as early work for future missions. NASA is focused on
launching the first mission, Exploration Mission-1
(EM-1), in 2020 to send an Orion spacecraft on the SLS (Space Launch
System) rocket from the modernized spaceport at Kennedy Space Center in
Florida on an uncrewed test flight before sending crew around the Moon
and back on the second mission, Exploration Mission-2 (EM-2) by 2023. 13)

- For the Orion
spacecraft that will fly on EM-1, engineers will continue stacking the
crew and service modules together at Kennedy and performing tests to
ensure the modules operate properly together. In the summer, the
stacked modules will fly aboard the agency’s Guppy aircraft to
NASA’s Plum Brook Station in Sandusky, Ohio, where together they
will undergo thermal vacuum testing as well as electromagnetic
interference and compatibility evaluations during a four-month test
campaign. When Orion returns from Ohio, it will undergo final checks
and processing before final preparations for launch and integration
with SLS.

- At the same time, Orion teams are
also working on the spacecraft and other critical systems for the
second mission that will carry a crew of astronauts around the Moon and
back. Engineers will continue outfitting and testing the crew module,
including pressuring the capsule to verify its structural integrity,
powering it on for the first time to ensure it can route commands
properly, and routing electrical and propulsion lines. Teams will also
perform welding for the environmental control system and fit it for the
outer back shells and heatshield.

- In preparation for the first
mission with crew, the agency will also test the spacecraft’s
launch abort system this June to demonstrate that it can carry the crew
to safety if an emergency were to happen on the way to space. During
the three-minute test, called Ascent Abort-2,
a booster will carry an Orion test vehicle to an altitude of 31,000
feet at more than 1,000 mph to test the launch abort system when the
spacecraft is under the highest aerodynamic loads it will experience
during a rapid climb into space.

The Rocket — Space Launch System (SLS)

- Technicians at NASA’s
Michoud Assembly Facility in New Orleans are nearly finished with
production of the first flight’s core stage, the largest element
of the most powerful rocket in the world. Technicians have almost
completed outfitting the engine section,
the complex bottom section of the core stage. Its sophisticated systems
feed propellant to the four RS-25 engines. The section will be joined
to the 130-foot-long liquid hydrogen propellant tank to form the
stage’s aft section. The aft section will then be connected to
the 66-foot forward section, which consists of the forward skirt, liquid oxygen tank, and intertank, in a horizontal configuration to form the full stage.

- The four core stage engines
for EM-1 will be delivered to Michoud later this year and installed
into the core stage engine section. NASA’s Pegasus barge will
move the completed stage to Stennis Space Center near Bay St. Louis,
Mississippi, where all four engines will roar to life to test the
completed stage.

- The team at Stennis has already completed two engine tests this year, concluding
a series of nine tests that began last August. This spring, NASA will
mark a major milestone to complete testing of all engines for the first
four SLS missions. Aerojet Rocketdyne has already started making the
engines for additional flights with the goal of reducing the costs of
manufacturing by at least 30 percent using smart manufacturing techniques.

- The last structural test article
for the core stage, a full-sized flight-like liquid oxygen tank, will
arrive at Marshall Space Flight Center in Huntsville, Alabama, this
summer on the Pegasus barge. Engineers will finish up structural
testing on the intertank and liquid hydrogen tank
and then begin with the liquid oxygen tank to push the hardware to the
limits under forces that exceed what the hardware will experience in
flight. Testing will also continue for multiple avionics and software
systems this year as well.

- Building and moving the 212-foot-tall core stage,
the largest rocket stage that NASA has ever built, has been one of the
most challenging aspects of SLS construction. NASA is applying this
experience to the core stage for the second mission, which is already
in production.

- Engineers at Marshall, are putting the finishing touches on the 30-foot-tall launch vehicle stage adapter
that will connect the top of the core stage to the interim cryogenic
propulsion stage, which was previously delivered to Kennedy. This year,
Pegasus will deliver the adapter to Kennedy. The SLS booster team in
Utah finished the ten solid rocket motor segments
needed for EM-1 earlier this year, and they will also be delivered to
Kennedy when needed, where they will join other booster parts.

- For the second SLS flight,
building is complete for most of the barrels, domes and other
structures needed to build the core stage for EM-2. Nearly all the
solid rocket motor sections for the boosters on the second mission are
cast and being outfitted. Teams are beginning work on additional parts
including the Orion Stage Adapter where other small payloads can be
carried, the launch vehicle stage adapter and the interim cryogenic
propulsion stage.

Kennedy Space Center — Ground Systems

- At Kennedy, the Exploration Ground
Systems team also has a busy year ahead in 2019. The crawler team will
finish engine maintenance and crawlerway conditioning, and engineers
will complete testing of the mobile launcher
in the Vehicle Assembly Building. In the spring, the mobile launcher
will roll back out to Pad 39B for its final testing at the pad. NASA
plans to award a contract for a second mobile launcher this year,
allowing more flexibility for upcoming exploration missions.

- At the pad, engineers will start to install a new liquid hydrogen tank
that will be used for EM-2. In firing rooms 1 and 2, final upgrades
will be made while the launch team finalizes the new countdown
procedures for SLS. Teams across the agency will participate in flight simulations
with the launch control center at Kennedy, mission control center at
Johnson and the SLS Engineering Support Center at Marshall. By the end
of 2019, EGS will begin processing the Orion crew capsule and SLS
hardware for launch of EM-1.

• January 31,
2019: NASA and its industry partners have completed manufacture and
checkout of 10 motor segments that will power two of the largest solid
propellant boosters ever built. The solid rocket fuel will help produce
8.8 million pounds of thrust (35.585 MN) to send NASA's Space Launch
System rocket on its first integrated flight with the Orion spacecraft.
Technicians at Northrop Grumman in Promontory, Utah, in coordination
with SLS program leads at NASA's Marshall Space Flight Center in
Huntsville, Alabama, finalized the fabrication of all 10 motor segments
and fitted them with key flight instrumentation. 14)

- They'll be shipped to NASA's
Kennedy Space Center in Florida, joined with booster forward and aft
assemblies, and readied to power the SLS Exploration Mission-1 test flight
when it launches from Kennedy. The uncrewed test launch will pave the
way for a new era of groundbreaking science and exploration missions
beyond low-Earth orbit, carrying crew and cargo to the Moon and on to
Mars. Marshall manages the Space Launch System for NASA.

• January 15, 2019: The largest
piece of structural test hardware for America’s new deep space
rocket, the SLS (Space Launch System), was loaded into Test Stand 4693
at NASA’s Marshall Space Flight Center in Huntsville, Alabama on
14 January 2019. The liquid hydrogen tank is part of the rocket’s
core stage that is more than 200 feet tall (61 m) with a diameter of
27.6 feet (8.4 m), and stores cryogenic liquid hydrogen and liquid
oxygen that will feed the vehicle’s RS-25 engines. The liquid
hydrogen tank test article is structurally identical to the flight
version of the tank that will comprise two-thirds of the core stage and
hold 537,000 gallons of supercooled liquid hydrogen at minus 423
degrees Fahrenheit (20.4 K). Dozens of hydraulic cylinders in the
215-foot-tall test stand will push and pull the tank, subjecting it to
the same stresses and loads it will endure during liftoff and flight. 15)

• December 14, 2018: Technicians at NASA's Michoud Assembly Facility in New Orleans, moved the largest piece of structural test hardware for America's new deep space rocket, the Space Launch System, from the factory to the dock where it was loaded onto NASA's barge Pegasus on 14 December 2018. 16)

- The liquid hydrogen tank
test article will make its way up the river to NASA’s Marshall
Space Flight Center in Huntsville, Alabama, where dozens of hydraulic
cylinders in Test Stand 4693 will push and pull on the giant tank,
subjecting it to the same stresses and loads it will endure during
liftoff and flight. The test hardware is structurally identical to the
flight version of the liquid hydrogen tank that will comprise
two-thirds of the core stage and hold 537,000 gallons of liquid hydrogen cooled to minus 423 degrees Fahrenheit (20.4 K).

• December 13, 2018: Northrop
Grumman Corporation along with NASA and Lockheed Martin successfully
performed a ground firing test of the abort motor for NASA’s
Orion spacecraft LAS (Launch Abort System) at Northrop Grumman’s
facility in Promontory, Utah (Figure 19).
The abort motor is a major part of the LAS, which provides an
enhancement in spaceflight safety for astronauts. The completion of
this milestone brings Orion one step closer to its first flight atop
NASA’s Space Launch System and to enabling humans to explore the
moon, Mars and other deep space destinations beyond low-Earth orbit. 17)

- “Our astronauts’
safety is our top priority,” said Steve Sara, director, launch
abort motor program, Northrop Grumman. “We never expect the
launch abort motor to be used, but just like an ejection seat in a
fighter pilot's aircraft, if they need it, it needs to work every
time.”

- The mission for
Orion’s LAS is to safely jettison the spacecraft and crew out of
harm’s way in the event of an emergency on the launch pad or
during initial launch ascent. Today’s abort motor test,
Qualification Motor-2, was the culmination of a series of component
tests conducted over the past few years in preparation for
qualification. Data from the test will confirm the motor can activate
within milliseconds and will perform as designed under cold
temperatures.

- The abort motor, which stands over
17 feet tall and spans three feet in diameter, has a manifold with four
exhaust nozzles. With its nozzles pointing skyward, it fired for five
seconds; the exhaust plume flames reached approximately 100 feet in
height. The high-impulse motor burns three times faster than a typical
motor of this size, delivering the thrust needed to pull the crew
module to safety. The motor achieved approximately 350,000 pounds of
thrust (1556 kN) in one eighth of a second, as expected. More analysis
will be performed in the coming weeks, but all initial results indicate
a successful test.

- Northrop Grumman’s next
major abort motor milestones include the Ascent Abort-2 Flight Test
(AA-2) set to take place at Cape Canaveral Air Force Station, Florida,
in 2019. Previous large-scale tests of the launch abort motor included
a development motor test in 2008, a pad abort test of the complete
launch abort system in 2010 and the Qualification Motor-1 static test
in 2017.

- For the AA-2 flight test, in
addition to the launch abort motor Northrop Grumman will also provide
the ATB (Abort Test Booster ), which will launch NASA’s Orion
spacecraft and LAS to on a preplanned trajectory to obtain data to be
used for LAS performance assessment. The ATB uses the same rocket motor
as the first stage of a Minotaur IV rocket.

- Northrop Grumman is responsible
for the launch abort motor through a contract to Lockheed Martin,
Orion’s prime contractor. The Orion LAS program is managed out of
NASA’s Langley Research Center in Virginia. Northrop Grumman
produces the abort motor at its Magna, Utah facility and the attitude
control motor at its Elkton, Maryland facility. The company also
manufactures the composite case for the abort motor at its facility in
Clearfield, Utah.

Figure 19:
Today’s test firing of the Northrop Grumman-manufactured launch
abort motor in Promontory, Utah, confirmed the motor can activate
within milliseconds and will perform as designed under cold
temperatures (image credit: Northrop Grumman, NASA)

• August 2018: Upper Stage and
Adapters: At the forward section of the rocket, just below the Orion
crew vehicle, is the OSA (Orion Stage Adapter), which holds the
secondary payload accommodations. For EM-1, the OSA is complete and was
delivered to EGS in February 2018. Made of a lightweight aluminum
alloy, the OSA measures 5.4 m in diameter by 1.5 m high. A diaphragm
just below the mounting brackets prevents launch gases from entering
the Orion spacecraft. 18)

- Sitting just below the OSA, the ICPS
(Interim Cryogenic Propulsion Stage), a modified Delta Cryogenic Second
Stage manufactured by ULA in Decatur, Ala. through a contract with
Boeing, supplies in-space propulsion for the Block 1 vehicle. The ICPS
will provide the TLI burn to send Orion toward the moon during the EM-1
mission. After entering its disposal trajectory with the OSA attached,
the ICPS will release the first seven CubeSats (Figure 20).

Figure 20:
Photo of the ICPS, which will provide in-space propulsion for the first
integrated flight of SLS and Orion, is complete (image credit: NASA)

• August 14, 2018: NASA
Administrator Jim Bridenstine made his first official visit to
NASA’s rocket factory, the Michoud Assembly Facility in New
Orleans, Louisiana, on Aug. 13, for tours and briefings on progress
building the Space Launch System rocket and Orion spacecraft. 19)

Figure 21: NASA Administrator Jim
Bridenstine speaks with members of the media in front of the massive
liquid hydrogen tank, which comprises almost two-thirds of the core
stage and holds 537,000 gallons (2032 cm3) of liquid
hydrogen cooled to minus 423º Fahrenheit (-252ºC). Innovative
processes are part of core stage manufacturing including joining the
thickest pieces of aluminum ever with self-reacting friction stir
welding. The liquid oxygen tank and liquid hydrogen tanks have the
thickest joints ever made with self-reacting friction stir welding
(image credit: NASA, Jude Guidry)

- Bridenstine, joined by Jody
Singer, acting director of NASA's Marshall Space Flight Center and
Keith Hefner, director of Michoud, toured the massive facility where
manufacturing and assembly of the largest and most complex parts of SLS
and Orion are underway. SLS will send the Orion spacecraft, astronauts
and critical hardware on bold exploration missions to the Moon and beyond.

- The tour highlighted the SLS core
stage which, flanked by two solid rocket boosters, will provide the
thrust to propel the vehicle to deep space. The administrator had the
opportunity to view SLS hardware just as engineers are putting the
finishing touches on the core stage parts by testing avionics,
installing special equipment inside the structures and applying thermal protection systems.

- Bridenstine also
viewed Orion's latest milestone, the welding completion of the primary
structure of the crew module, or pressure vessel, by engineers at
Michoud. The pressure vessel is the primary structure that holds the
pressurized atmosphere astronauts will breathe to allow them to work in
the harsh environment of deep space. This pressure vessel will carry
the first astronauts to missions beyond the Moon on Exploration Mission-2.

- "This is a critical piece of
America's architecture for our return to the Moon and ultimately, it's
a strategic capability for the United States of America," said
Bridenstine. "I cannot overstate how important this capability is to
America and how all of the team members who work here are contributing
to a capability where countries around the world are seeking to partner
with the United States as we return to the surface of the Moon and into
orbit around the Moon."

• July 31, 2018: The first
major piece of core stage hardware for NASA's SLS (Space Launch System)
rocket has been assembled and is ready to be joined with other hardware
for Exploration Mission-1. The forward skirt will connect the upper
part of the rocket to the core stage and house many of the flight
computers, or avionics. 20)

Figure 22: The first major piece
of core stage hardware for NASA's Space Launch System rocket has been
assembled and is ready to be joined with other hardware for Exploration
Mission-1. The forward skirt will connect the upper part of the rocket
to the core stage and house many of the flight computers, or avionics
(image credit: NASA, Eric Bordelon)

- The backbone of the world's most powerful rocket, the 212-foot-tall (64.6 m) core stage, will contain the SLS rocket's four RS-25 rocket engines,
propellant tanks, flight computers and much more. Though the smallest
part of the core stage, the forward skirt will serve two critical
roles. It will connect the upper part of the rocket to the core stage
and house many of the flight computers, or avionics.

- "Completion of the core stage
forward skirt is a major step in NASA's progress to the launch pad,"
said Deborah Bagdigian, lead manager for the forward skirt at the
agency's Marshall Space Flight Center in Huntsville, Alabama. "We're
putting into practice the steps and processes needed to assemble the
largest rocket stage ever built. With the forward skirt, we are
improving and refining how we'll conduct final assembly of the rest of
the rocket."

- On July 24, the
forward skirt assembly was wrapped up with the installation of all its
parts. As part of forward skirt testing, the flight computers came to
life for the first time as NASA engineers tested critical avionic
systems that will control the rocket’s flight. The construction,
assembly and avionics testing occurred at NASA's Michoud Assembly
Facility in New Orleans.

- Located throughout the core stage,
the avionics are the rocket's "brains," controlling navigation and
communication during launch and flight. It is critical that each of the
avionics units is installed correctly, work as expected and communicate
with each other and other components, including the Orion spacecraft
and ground support systems.

- "It was amazing to see the
computers come to life for the first time" said Lisa Espy, lead test
engineer for SLS core stage avionics. "These are the computers that
will control the rocket as it soars off the pad for Exploration
Mission-1."

- The forward skirt test series was
the first of many that will verify the rocket's avionics will work as
expected during launch. The tests show the forward skirt was built
correctly, and that all components and wiring on the inside have been
put together and connected properly and are sending data over the lines
as expected.

- The avionic computers ran
"built-in tests" that Espy compares to the internal diagnostic tests
performed by an automobile when first started. All of the health and
data status reports came back as expected. The tests were a success and
did not return any error codes. Such error codes would be similar to a
check engine light on a car.

- The successful tests give the team
the confidence needed to move forward with avionics installations in
the core stage intertank and engine section. With more hardware and
more interfaces, the installation in the intertank will be more
complex, and the complexity will ramp up even more as the team moves to
the engine section, introducing hydraulics and other hardware needed
for the rocket's engines.

- Engineers will perform standalone
tests on each component as they are completed. Once the forward and aft
joins are integrated, they will perform a final integrated function
test, testing all the core stage's avionics together.

- The fully integrated core stage
and its four RS-25 engines will then be fired up during a final test
before launch. At NASA's Kennedy Space Center in Florida, the core
stage will be stacked with the upper part of the rocket, including
Orion, and joined to the rocket's twin solid rocket boosters, in
preparation for EM-1.

• July 10, 2018: Aerojet
Rocketdyne recently passed a key milestone in preparation for the
Ascent Abort Test (AA-2) next year with the successful casting of the
Jettison Motor for the Lockheed Martin-built Orion spacecraft's LAS
(Launch Abort System). AA-2 is a full-stress test of NASA's Orion LAS,
which includes the Jettison Motor built by Aerojet Rocketdyne. The
Orion Jettison Motor is used to separate the LAS from Orion as it makes
its way to space and is the only motor on the escape system to activate
in all mission scenarios. 21)

Figure 23: The Jettison Motor
built by Aerojet Rocketdyne for the Lockheed Martin-built Orion
spacecraft's LAS (Launch Abort System) that will be tested during the
Ascent Abort Test (AA-2) next year (image credit: Aerojet Rocketdyne)

- In the unlikely event of an
emergency on the launch pad or during ascent, the LAS would activate
within milliseconds to whisk Orion and its astronaut crew to safety.
Once Orion reaches a safe distance from the rocket, the Orion Jettison
Motor would ignite to separate the LAS structure from the spacecraft,
which could then deploy its parachutes for a safe landing.

- During the AA-2 test, a solid
rocket booster will launch a fully functional LAS and an Orion test
vehicle to an altitude of 31,000 feet (~9.5 km) at Mach 1.3 (over 1,000
mph) to test out the functionality of the LAS system prior to flying
humans. The Jettison Motor will fire last in the test sequence.

- "Every time our engineers work on
products supporting the Orion spacecraft or the Space Launch System
rocket, they have astronaut safety front and center of mind," said
Aerojet Rocketdyne CEO and President Eileen Drake. "The AA-2 test is a
critical step to testing the Launch Abort System and our Jettison Motor
and ensuring our astronauts always return home safely to their
families."

- The Orion Jettison Motor, which
generates 40,000 pounds of thrust (177.928 kN), uses a propellant that
is poured into a motor casing, where it cures over a period of several
days to form a solid, stable cast that burns in a precisely controlled
fashion.

- The AA-2 Jettison Motor casting
took place at Aerojet Rocketdyne's motor production facility in
Sacramento, California. The completed motor will now be shipped to
NASA's Kennedy Space Center for integration with the LAS by Lockheed
Martin.

• April 3, 2018: NASA's Super
Guppy aircraft prepares to depart the U.S. Army’s Redstone
Airfield in Huntsville, Alabama, April 3, with flight hardware for
NASA’s Space Launch System – the agency’s new,
deep-space rocket that will enable astronauts to begin their journey to
explore destinations far into the solar system. The Orion stage
adapter, the top of the rocket that connects SLS to Orion is loaded
into the Guppy, which will deliver it to NASA’s Kennedy Space
Center in Florida for flight preparations. On Exploration Mission-1,
the first integrated flight of SLS and the Orion spacecraft, the
adapter will carry 13 CubeSats as secondary payloads. SLS will send
Orion beyond the Moon, about 280,000 miles from Earth. This is farther
from Earth than any spacecraft built for humans has ever traveled. 22)

• December 22, 2017: The
booster avionics system for the SLS (Space Launch System) rocket
completed system-level qualification testing in October 2017. Engineers
simulated the booster avionics operations in a systems integration lab
at NASA’s Marshall Space Flight Center in Huntsville, Alabama,
where all the avionics boxes and electronics were tested. The tests
verified the fidelity of the system. Two five-segment rocket boosters,
developed by Orbital ATK, will provide 80 percent of the thrust for the
first two minutes of flight. The booster avionics, receiving commands
from the SLS flight computers in the core stage, provide 80 percent of
the control authority for the rocket during the first two minutes of
flight. Key interactions confirmed during qualification testing
included the ability to initiate booster ignition, control the booster
during flight, terminate flight, and triggering core stage separation. 23)

• December 15,
2017: When NASA’s Orion spacecraft hurtles toward Earth’s
surface during its return from deep-space missions, the capsule’s
system of 11 parachutes
will assemble itself in the air and slow the spacecraft from 300 mph to
a relatively gentle 20 mph for splashdown in the Pacific Ocean in the
span of about 10 minutes. As the astronauts inside descend toward the
water on future missions, their lives will be hanging by a series of
threads that have been thoroughly ruggedized, tested and validated to
ensure the parachute-assisted end of Orion missions are a success. 24)

- Through a series of tests in the
Arizona desert, the engineers refining Orion’s parachutes have
made the road to certifying them for flights with astronauts look easy,
including a successful qualification test Dec. 13 that evaluated a
failure case in which only two of the systems three orange and white
main parachutes deploy after several other parachutes in the system
used to slow and stabilize Orion endure high aerodynamic stresses. But
behind the scenes, engineers are working hard to understand and perfect
the system that must be able to work across a broad range of potential
environmental conditions and bring the crew home.

- While Orion’s parachutes may
look similar to those used during the Apollo-era to the untrained eye,
engineers can’t simply take that parachute system and scale it up
to accommodate Orion’s much larger size. Through testing and
analysis, technicians have developed Orion’s parachutes to be
lighter, better understood and more capable than Apollo’s. NASA
has also been able to adjust the system as elements of the spacecraft,
such as attachment points, have matured.

- “Through our testing,
we’ve addressed some known failures that can happen in complex
parachute systems to make the system more reliable,” said Koki
Machin, chief engineer for the system. “We built upon the strong
foundation laid by Apollo engineers and figured out how to manage the
stresses on the system during deployment more efficiently, decrease the
mass of the parachutes by using high tech fabric materials rather than
metal cables for the risers that attach the parachute to the
spacecraft, and improve how we pack the parachute into Orion so they
deploy more reliably.”

- Orion’s parachute system is
also incredibly complex. About 10 miles of Kevlar lines attach the
spacecraft to the outer rim of nearly 12,000 square feet (~1110 m2)
of parachute canopy material – over four times the average square
footage of a house – and must not get tangled during deployment.
In addition to the fabric parachutes themselves, there are cannon-like
mortars that fire to release different parachutes. Embedded in several
parachutes are fuses set to burn at specific times that ignite charges
to push blades through bullet proof materials at precise moments,
slowly unfurling the parachutes to continue the sequential phases of
the deployment sequence. All of these elements must be developed to be
reliable for the various angles, wind conditions and speeds in which
Orion could land.

- With the analysis capabilities
that exist today and the historical data available, engineers have
determined that approximately 20-25 tests, rather than the more than
100 performed during the Apollo era, will give them enough
opportunities to find areas of weakness in Orion’s parachute
system and fix them. After the three remaining final tests next year,
the system will be qualified for missions with astronauts.

- “There are things we can
model with computers and those we can’t. We have to verify the
latter through repeated system tests by dropping a test article out of
a military aircraft from miles in altitude and pushing the parachutes
to their various limits,” said CJ Johnson, project manager for
the parachute system. “Lots of subtle changes can affect
parachute performance and the testing we do helps us account for the
broad range of possible environments the parachutes will have to
operate in.”

- Orion parachute engineers have also provided data and insight from the tests to NASA’s Commercial Crew Program partners.
NASA has matured computer modeling of how the system works in various
scenarios and helped partner companies understand certain elements of
parachute systems, such as seams and joints, for example. In some
cases, NASA’s work has provided enough information for the
partners to reduce the need for some developmental parachute tests.

- “Orion’s parachute
system is an extremely lightweight, delicate collection of pieces that
absolutely must act together simultaneously or it will fail,”
said Machin. “It alone, among all the equipment on the crew
module, must assemble itself in mid-air at a variety of possible
velocities and orientations.”

Figure 25: NASA
is testing Orion’s parachutes to qualify the system for missions
with astronauts (image credits: U.S. Army)

• November 8, 2017: NASA is
providing an update on the first integrated launch of the Space Launch
System (SLS) rocket and Orion spacecraft after completing a
comprehensive review of the launch schedule. This uncrewed mission,
known as Exploration Mission-1 (EM-1) is a critical flight test for the
agency’s human deep space exploration goals. EM-1 lays the
foundation for the first crewed flight of SLS and Orion, as well as a
regular cadence of missions thereafter near the Moon and beyond. 25)

- The review follows an earlier
assessment where NASA evaluated the cost, risk and technical factors of
adding crew to the mission, but ultimately affirmed the original plan
to fly EM-1 uncrewed. NASA initiated this review as a result of the
crew study and challenges related to building the core stage of the
world’s most powerful rocket for the first time, issues with
manufacturing and supplying Orion’s first European service
module, and tornado damage at the agency’s Michoud Assembly
Facility in New Orleans.

- “While the review of the
possible manufacturing and production schedule risks indicate a launch
date of June 2020, the agency is managing to December 2019,” said
acting NASA Administrator Robert Lightfoot. “Since several of the
key risks identified have not been actually realized, we are able to
put in place mitigation strategies for those risks to protect the
December 2019 date.”

- The majority of work on
NASA’s new deep space exploration systems is on track. The agency
is using lessons learned from first time builds to drive efficiencies
into overall production and operations planning. To address schedule
risks identified in the review, NASA established new production
performance milestones for the SLS core stage to increase confidence
for future hardware builds. NASA and its contractors are supporting
ESA’s (European Space Agency) efforts to optimize build plans for
schedule flexibility if sub-contractor deliveries for the service
module are late.

- NASA’s ability to meet its
agency baseline commitments to EM-1 cost, which includes SLS and ground
systems, currently remains within original targets. The costs for EM-1
up to a possible June 2020 launch date remain within the 15 percent
limit for SLS and are slightly above for ground systems. NASA’s
cost commitment for Orion is through Exploration Mission-2. With
NASA’s multi-mission approach to deep space exploration, the
agency has hardware in production for the first and second missions,
and is gearing up for the third flight. When teams complete hardware
for one flight, they’re moving on to the next.

- As part of the review, NASA now
plans to accelerate a test of Orion’s launch abort system ahead
of EM-1, and is targeting April 2019. Known as Ascent-Abort 2, the test
will validate the launch abort system’s ability to get crew to
safety if needed during ascent. Moving up the test date ahead of EM-1
will reduce risk for the first flight with crew, which remains on track
for 2023.

• November 8, 2017: Lift off at
the end of the countdown is just the first phase in a launch. Two
minutes in, booster separation occurs ­– a critical stage in
flight, with little room for error. Engineers at NASA’s Langley
Research Center in Hampton, Virginia, are doing their part to support
NASA’s new deep space rocket, the SLS (Space Launch System). The
rocket will be capable of sending the Orion crew vehicle and other
large cargos on bold new missions beyond Earth orbit. To understand the
aerodynamic forces as booster separation motors fire and push the solid
rocket boosters away from the rocket’s core, Langley engineers
are testing a 35-inch SLS model in Block 1B 105-metric ton evolved
configuration in the Unitary Plan Wind Tunnel using a distinct pink
paint. The pressure-sensitive paint works by reacting with oxygen to
fluoresce at differing intensities, which is captured by cameras in the
wind tunnel. Researchers use that data to determine the airflow over
the model and which areas are seeing the highest pressure. 26)

• October 19, 2017: NASA
engineers conducted a full-duration, 500-second test of RS-25 flight
engine E2063 on the A-1 Test Stand at SSC (Stennis Space Center) on
Oct. 19, 2017. Once certified, the engine is scheduled to help power
NASA’s new Space Launch System rocket on its EM-2 (Exploration
Mission-2). The test was part of Founders Day Open House activities at
Stennis. 27)

- Engine E2063 is
scheduled for use on NASA’s second mission of SLS and Orion,
known as EM-2. The first integrated flight test of SLS and Orion, EM-1
(Exploration Mission-1), will be an uncrewed final test of the rocket
and its systems. The EM-2 flight will be the first to carry astronauts
aboard the Orion spacecraft, marking the return of humans to deep space
for the first time in more than 40 years.

• September 22, 2017: Following
a series of issues over the last year with the Core Stage for the first
flight of the Space Launch System rocket, the launch dates for both the
EM-1 and EM-2 flights are beginning to align, with EM-1 now targeting
'No Earlier Than' 15 December 2019 and EM-2 following on 1 June 2022.
Additionally, the EM-3 flight has gained its first notional mission
outline, detailing a flight to Near-Rectilinear Halo Orbit to deploy
the Hab (Habitat) module for the new Deep Space Gateway. 28)

- The first flight of any new rocket
is bound to encounter design and initial production delays. And
NASA’s SLS (Space Launch System ) rocket is been no stranger to
those sort of anticipated effects. - Following a misalignment in the
installation of the main welding machine at the Michoud Assembly
Facility (MAF), welding for the certification elements for the new SLS
core stage Liquid Hydrogen (LH2) and Liquid Oxygen (LOX) tanks picked
up.

- After the initial LH2
qualification tanks were welded, a change to the welding
machine’s pin was made – a change that resulted in segment
welds on the EM-1 LH2 flight tank being too brittle to meet flight
specification requirements.

- This pin change and subsequent
issue led to the understanding that the LH2 flight tank for EM-1 was no
longer flight worthy and thus could not be used for EM-1.

- A plan was then put in place to
restore the welding machine’s previously used pin – the one
that welded all the Core Stage test articles that have thus far passed
all qualification and acceptance testing – and use the upcoming
weld for the EM-2 flight LH2 tank as the new LH2 tank for the EM-1
flight.

- However, less than a week after
the EM-1 LH2 flight tank issue became known, a worker at MAF damaged
the aft dome section of the qualification article for the Core Stage
LOX tank.

- In all, these production issues
quickly made the Core Stage’s timeline for EM-1’s then-2018
launch date impossible.

- Earlier this year, NASA
acknowledged this and announced that EM-1 was slipping to sometime in
2019 – though that was already understood to be “Q4
2019.”

The information compiled and edited in this article was provided byHerbert
J. Kramer from his documentation of: ”Observation of the Earth
and Its Environment: Survey of Missions and Sensors” (Springer
Verlag) as well as many other sources after the publication of the 4th
edition in 2002. - Comments and corrections to this article are always
welcome for further updates (herb.kramer@gmx.net).